1. Field of the Invention
The present invention relates to a stylus support assembly for a gauge for a metrological instrument for measuring surface form such as roundness and/or surface finish parameters, such as surface texture or roughness.
2. Discussion of the Background
Metrological instruments are known in which a stylus is mounted on an arm so as to follow the surface form or finish of a workpiece during relative movement of the arm and the workpiece. A transducer outputs a signal in accordance with movement of the stylus relative to the arm. Metrological instruments are normally made so that the stylus is removable and replaceable. This is to allow a different stylus to be fitted to the same machine. This may be necessary to allow the stylus length to be changed or to change the particular stylus tip, in accordance with the workpiece being measured and the accuracy required. However, the constant insertion and removal of different styli means that the gauge must be constantly recalibrated and leads to inaccurate readings from the transducer if recalibration is not carried out.
According to one aspect of the present invention there is provided a stylus support assembly which supports a stylus in a more stable and reliable manner.
According to one aspect of the present invention, there is further provided a stylus support assembly for supporting a stylus for use in a gauge for a metrological instrument, the support assembly comprising two members resiliently connected so as to provide a stylus force in use of the assembly to enable the stylus tip to be pressed against the surface of the body to be measured and keep contact with that surface.
The members may be connected at an angle which is typically within a range of 2xc2x0 to 3xc2x0 from the perpendicular to the gauge axis. The stylus force can be changed by changing the resilience and/or the angle of the connecting means.
In another aspect, the present invention provides a one-piece stylus. A stylus tip can be mounted at the front end. A shaft for holding a core of a transducer ferrite, can be located at the rear end of the stylus.
In one aspect, the invention provides a particular construction of stylus support means to improve stylus stability.
A stylus support assembly embodying the invention is easy to manufacture and assemble.